Real-time Traffic Information and Alerts for England

The UK Highway Agency has real-time traffic condition feeds that cover all of the Highway Agency's roads England. You can look at conditions across all of England, in specific areas, or specific highways.

http://www.highways.gov.uk/traffic/11278.aspx

Also of interest is this traffic alert feed from London Transport that covers all of London.

http://trafficalerts.tfl.gov.uk/rss/trafficalertsall.rss

If only we could freely get this kind of data here in the states...